In one type of optical system, computer generated images are projected onto a screen or other suitable surface for viewing by a large number of people simultaneously. An important aspect of such a system is to enable a user to enter information interactively into the system to modify images, or generate additional images during presentations. In one successful arrangement, a user directs a high intensity light from a device, such as a laser pointer, onto a projected image to provide auxiliary control information for the system.
Such a system generally includes a video information source, such as a computer, and a display projection arrangement, such as an overhead projector for projecting video information onto a viewing surface. An image processing arrangement detects and processes the displayed image reflecting from the viewing surface. Such a system detects the high intensity light images produced by the hand held light generating device, and discriminates them from background ambient light as well as the light produced by the video information sources. In this manner, light signals from the hand held light generating device can be detected on the viewing surface and then used by the system for modifying subsequently the projected video information. Such an optical input system is described in greater detail in the above-mentioned U.S. patent application Ser. No. 07/433,029.
While such an optical system and method of using it has proven highly satisfactory, the light generating device of such a system must be held in a very steady manner to assure the accurate communication of the user generated optical information. To help facilitate the accurate communication of such information, the light generating device generally includes a dual beam mode of operation. In this regard, the light generating device is activated by the user manually to generate a low intensity light beam to help the user position the auxiliary light beam on a desired location on the viewing screen without being sensed by the auxiliary input system. Once the low intensity beam is properly positioned in response to the actuation of a switch, the light generating device is then activated manually by the user to produce a high intensity light beam indicative of the auxiliary light information to interact with the computer. In this manner, the high intensity light signal from the hand held light generating device can generate auxiliary information for emulating a mouse. Such a dual beam light generating device and method of using it is described in greater detail in the above-mentioned copending U.S. patent application Ser. No. 07/901,253.
While such a light generating input device and input method has proven highly satisfactory for many applications, it would be desirable to provide a new and improved optical input arrangement and method that would more closely emulate both the single click and double click mouse features of a mouse device in a more convenient manner. More particularly, while the dual beam feature greatly facilitates the single click feature, it has been difficult for a user to use such a device for the double click feature.
The optical auxiliary input system can perform various different control functions, including those performed by conventional computer mouse input device. In this regard, the optical input system can perform such operations as a "single click" a "double click" and a tracking operation as is well known in the art. It is very important that the optical input device be able to function in a similar manner as a conventional computer mouse, since many application computer programs used today, are able to interface with a conventional mouse device for control purposes. In this manner, the optical input system should be compatible, more completely, with conventional application computer programs.
In this regard, the user must hold the light generating input device in such a steady manner, that the same location on the viewing screen is illuminated while the user turns the auxiliary light beam on and off in a repeated sequence. Thus, if the beam is not held at the same location on the viewing surface during the double click operation, the signal processing unit of the optical system can under certain circumstances misinterpret the auxiliary light information. For example, such a double actuation of the light could be interpreted as two, separate single click operations at two different locations on the screen.
One manner of overcoming this problem is to have a much larger area on the screen to be hit by the high intensity light beam so that if the hand of the user should move inadvertently, the double click would still be interpreted correctly. However, this would require undue and unwanted restrictions on application computer programs. It would be far more desirable to have the optical auxiliary input device be more fully compatible with the existing computer program formats.
Therefore, it would be highly desirable to have a new and improved optical auxiliary input arrangement and input method to more closely emulate a computer mouse type input device for use with an optical system. Such an arrangement and method should enable a user to emulate the mouse without the need of holding the auxiliary light image so steady that the auxiliary light information is projected precisely on the same location on the viewing screen during a double click operation.
The arrangement and method should also respond to the user in a fast and reliable manner to more completely emulate the functional features of a mouse input device. In this regard, such an arrangement should enable either a conventional computer mouse or the optical auxiliary input device, a light generating device, to communicate with the same video information source, whenever desired by the user, for modifying or changing displayed images in a simple and reliable manner.